Antenna device

Abstract

An antenna device is provided with a plate-shaped grounded wiring board, a plate-shaped antenna element arranged to oppose the wiring board and spaced apart therefrom, two grounding leg parts which are disposed at ends of the antenna element and each of which has an extending tip connected to the wiring board, and a feeding leg part which is disposed at an end of the antenna element and which has an extending tip that connects to a transmission circuit or a reception circuit. A planar shape formed by the ends at which the plurality of grounding leg parts are disposed and the end at which the feeding leg part is disposed has point symmetry.

What is claimed is: 
     
       1. An antenna device comprising:
 a plate-shaped antenna element arranged to oppose a wiring board that is grounded, with a gap formed between the antenna element and the wiring board; 
 a plurality of grounding leg parts arranged at respective outer side parts of the antenna element and having respective extending tips connected to the wiring board; 
 a feeding leg part arranged at a corresponding outer side part of the antenna element and having an extending tip that connects to a transmission circuit or a reception circuit; 
 a plurality of rectangular cutout parts respectively formed at the outer side parts of the antenna element and extending toward an inner side of the antenna element; and 
 a plurality of sidewall parts respectively arranged at the outer side parts of the antenna element and extending toward the wiring board, 
 wherein the antenna element includes
 a surface opposing the wiring board and having a regular polygonal shape in a plan view, 
 a plurality of corner parts respectively corresponding to vertexes of the regular polygonal shape, and 
 a plurality of side parts respectively corresponding to sides of the regular polygonal shape, 
 
 wherein each of the side parts is arranged between two adjacent corner parts, and has a first portion closer to one of the two adjacent corner parts and a second portion closer to the other of the two adjacent corner parts, 
 wherein the feeding leg part is arranged at one of the corner parts of the antenna element, and the plurality of grounding leg parts are arranged at remaining corner parts of the antenna element, 
 wherein each of the plurality of rectangular cutout parts is formed at the first portion of the side part, and 
 wherein each of the plurality of sidewall parts is formed at the second portion of the side part. 
 
     
     
       2. The antenna device as claimed in  claim 1 , wherein the regular polygonal shape of the surface of the antenna element is a square shape in the plan view, and the plurality of leg parts, the feeding leg part, the plurality of rectangular cutout parts, and the plurality of sidewall parts are located at rotationally symmetric positions. 
     
     
       3. The antenna device as claimed in  claim 1 , further comprising:
 the wiring board, 
 wherein the wiring board is plate-shaped. 
 
     
     
       4. The antenna device as claimed in  claim 3 , wherein
 the wiring board includes a hole, and a grounding part, and 
 the extending tip end of the feeding leg part passes through the hole in the wiring board so as not to make contact with the grounding part of the wiring board. 
 
     
     
       5. The antenna device as claimed in  claim 1 , wherein the regular polygonal shape of the surface of the antenna element is a square shape in the plan view, and the plurality of grounding leg parts and the feeding leg part are located at rotationally symmetric positions. 
     
     
       6. The antenna device as claimed in  claim 5 , wherein the plurality of sidewall parts are located at rotationally symmetric positions. 
     
     
       7. The antenna device as claimed in  claim 5 , wherein the plurality of rectangular cutout parts are located at rotationally symmetric positions.